Field of the Invention
The invention relates to the field of sensing the angular orientation of a magnetic field. In particular, the invention relates to a sensor for sensing an angular orientation of a magnet producing a magnetic field, and this way, also rotational speeds or related magnitudes can be derived. Corresponding devices find application in many areas, e.g., in position sensing and in rotation speed measuring, e.g., in electric motors and in automotive and aircraft industry.
Description of Related Art
In WO 2008/145662 A1, a magnetic field sensor for measuring a direction of a magnetic field in a plane is presented, which includes a sensing structure including a ring-shaped well, a plurality of contacts of equal size placed at equal distance from each other along the ring-shaped well, and an electronic circuit including a plurality of electronic switches associated with the contacts of the sensing structure, a logic block for controlling the electronic switches, at least one current source, a means for measuring a difference between a first voltage and a second voltage, a timing circuit providing a control signal for controlling the logic block and providing a reference signal. The logic block is adapted to close and open the electronic switches under the control of the control signal according to a predetermined scheme such that a predetermined number of contacts of the plurality of contacts form a vertical Hall element that is supplied with current from the at least one current source and that has two contacts connected to the means for measuring, and such that the vertical Hall element is moved in steps along the ring-shaped well. Also provided is a means for measuring a phase shift between the reference signal and an output signal of the voltage measuring means.
From WO 2009/124969 A1, a magnetic field sensor for measuring a direction of a magnetic field in a plane is known which includes two sensing structures that can be operated as a rotating Hall element. The two Hall elements are rotated in discrete steps in opposite directions. Such a magnetic field sensor can be used as current sensor for measuring a primary current flowing through a conductor.
WO 2012/151707 discloses a method for sensing an angular orientation of a magnetic field including:
a) providing a set of N≧2 Hall effect devices, each having a detection direction and including two pairs of connectors;
b) providing at least one band pass filter having a fundamental frequency f=1/Tf;
c) providing at least one current source for outputting an electrical current at its output; wherein a particular way of wiring both pairs of connectors of a Hall effect device to the output of the current source or to the band pass filter is referred to as a “wiring scheme”;d1) applying, during a first time period of a duration 0.5 Tf and in a specific sequence of the N Hall effect devices, to each of the N Hall effect devices a respective wiring scheme Wi+, during respective subsequent time periods of durations ti; andd2) applying, during a second time period of a duration 0.5 Tf, subsequent to the first time period of a duration 0.5 Tf, and in the same specific sequence of the N Hall effect devices, to each of the N Hall effect devices a respective wiring scheme Wi−, during respective subsequent time periods of the same durations ti;wherein each of the wiring schemes Wi+ is an orthogonal and reverse wiring scheme of the respective other wiring scheme Wi−; ande) deriving from signals outputted by the band pass filter in reaction to carrying out steps d1) and d2) an output signal indicative of the angular orientation;wherein i=1, . . . , N.